A search for high mass resonances decaying to tau(+)tau( ) in pp collisions at root s=7 TeV with the ATLAS detector

Texto completo

(1)Physics Letters B 719 (2013) 242–260. Contents lists available at SciVerse ScienceDirect. Physics Letters B www.elsevier.com/locate/physletb. A to √ search for high-mass resonances decaying ✩ s = 7 TeV with the ATLAS detector. τ + τ − in pp collisions at. .ATLAS Collaboration a r t i c l e. i n f o. Article history: Received 24 October 2012 Received in revised form 18 December 2012 Accepted 19 January 2013 Available online 26 January 2013 Editor: H. Weerts Keywords: Exotics Z Ditau Resonance Search. a b s t r a c t This Letter presents √ a search for high-mass resonances decaying into τ + τ − final states using proton– proton collisions at s = 7 TeV produced by the Large Hadron Collider. The data were recorded with the ATLAS detector and correspond to an integrated luminosity of 4.6 fb−1 . No statistically significant excess above the Standard Model expectation is observed; 95% credibility upper limits are set on the cross section times branching fraction of Z resonances decaying into τ + τ − pairs as a function of the resonance mass. As a result, Z bosons of the Sequential Standard Model with masses less than 1.40 TeV are excluded at 95% credibility. © 2013 CERN. Published by Elsevier B.V. Open access under CC BY-NC-ND license.. 1. Introduction Many extensions of the Standard Model (SM), motivated by grand unification, predict additional heavy gauge bosons [1–6]. As lepton universality is not necessarily a requirement for these new gauge bosons, it is essential to search in all decay modes. In particular, some models with extended weak or hypercharge gauge groups that offer an explanation for the high mass of the top quark predict that such bosons preferentially couple to third-generation fermions [7]. This Letter presents the first search for high-mass resonances decaying into τ + τ − pairs using the ATLAS detector [8]. The Sequential Standard Model (SSM) is a benchmark model that con tains a heavy neutral gauge boson, Z SSM , with the same couplings to fermions as the Z boson of the SM. This model is used to optimise the event selection of the search; limits on the cross section times τ + τ − branching fraction of a generic neutral resonance are reported. Direct searches for high-mass ditau resonances have been performed previously by the CDF [9] and CMS [10] collaborations. The latter search sets the most stringent 95% confidence level limits and excludes Z SSM masses below 1.4 TeV, with an expected limit √ of 1.1 TeV, using 4.9 fb−1 of integrated luminosity at s = 7 TeV. Indirect limits on Z bosons with non-universal flavour couplings have been set using measurements from LEP and LEP II [11] and. E-mail address: [email protected].. translate to a lower bound on the Z mass of 1.09 TeV. For com parison, the most stringent limits on Z SSM in the dielectron and dimuon decay channels combined are 2.2 TeV from ATLAS [12] and 2.3 TeV from CMS [13]. Tau leptons can decay into a charged lepton and two neutrinos (τlep = τe or τμ ), or hadronically (τhad ), predominantly into one or three charged pions, a neutrino and often additional neutral pions. The τhad τhad (branching ratio, BR = 42%), τμ τhad (BR = 23%), τe τhad (BR = 23%) and τe τμ (BR = 6%) channels are analysed. Due to the different dominant background contributions and signal sensitivities, each channel is analysed separately and a statistical combination is used to maximise the sensitivity. While the expected natural width of the Z SSM is small, approximately 3% of the Z mass, the mass resolution is 30–50% in τ + τ − decay modes due to the undetected neutrinos from the tau decays. Therefore, a counting experiment is performed in all analysis channels from events that pass a high-mass requirement. 2. Event samples The data used in this search were recorded with the ATLAS detector √ in proton–proton (pp) collisions at a centre-of-mass energy of s = 7 TeV during the 2011 run of the Large Hadron Collider (LHC) [14]. The ATLAS detector consists of an inner tracking detector surrounded by a thin superconducting solenoid, electromagnetic (EM) and hadronic calorimeters, and a muon spectrometer incorporating large superconducting toroid magnets. Each subdetector is divided into barrel and end-cap components.. 0370-2693/ © 2013 CERN. Published by Elsevier B.V. Open access under CC BY-NC-ND license. http://dx.doi.org/10.1016/j.physletb.2013.01.040.

(2) ATLAS Collaboration / Physics Letters B 719 (2013) 242–260. Only data taken with pp collisions in stable beam conditions and with all ATLAS subsystems operational are used, resulting in an integrated luminosity of 4.6 fb−1 . The data were collected using a combination of single-tau and ditau triggers, designed to select hadronic tau decays, and single-lepton triggers. The τhad τhad channel uses events passing either a ditau trigger with transverse energy (E T ) thresholds of 20 and 29 GeV, or a single-tau trigger with an E T threshold of 125 GeV. The τμ τhad and τe τμ channels use events passing a single-muon trigger with a transverse momentum (p T ) threshold of 18 GeV, which is supplemented by accepting events that pass a single-muon trigger with a p T threshold of 40 GeV that operates only in the barrel region but does not require a matching inner detector track. The τe τhad channel uses events passing a single-electron trigger with p T thresholds in the range 20–22 GeV, depending on the data-taking period. Events that pass the trigger are selected if the vertex with the largest sum of the squared track momenta has at least four associated tracks, each with p T > 0.5 GeV. Monte Carlo (MC) simulation is used to estimate signal efficiencies and some background contributions. MC samples of background processes from W + jets and Z /γ ∗ + jets (enriched in high-mass Z /γ ∗ → τ τ ) events are generated with ALPGEN 2.13 [15], including up to five additional partons. Samples of t t̄, W t and diboson (W W , W Z , and Z Z ) events are generated with MC@NLO 4.01 [16,17]. For these MC samples, the parton showering and hadronisation is performed by HERWIG 6.520 [18] interfaced to JIMMY 4.31 [19] for multiple parton interactions. Samples of s-channel and t-channel single top-quark production are generated with AcerMC 3.8 [20], with the parton showering and hadronisation performed by PYTHIA 6.425 [21]. Sam ples of Z SSM signal events are generated with PYTHIA 6.425, for eleven mass hypotheses ranging from 500 to 1750 GeV in steps of 125 GeV. In all samples photon radiation is performed by PHOTOS [22], and tau lepton decays are generated with TAUOLA [23]. The choice of parton distribution functions (PDFs) depends on the generator: CTEQ6L1 [24] is used with ALPGEN, CT10 [25] with MC@NLO and MRST2007 LO∗ [26] with PYTHIA and AcerMC. The Z /γ ∗ cross section calculated at next-to-next-to-leading order (NNLO) using PHOZPR [27] with MSTW2008 PDFs [28] is used to derive mass-dependent K -factors that are applied to the leading order Z /γ ∗ + jets and Z → τ τ cross sections. The W + jets cross section is calculated at NNLO using FEWZ 2.0 [29,30]. The t t̄ cross section is calculated at approximate NNLO [31–33]. The cross sections for single-top production are calculated at next-tonext-to-leading logarithm for the s-channel [34] and approximate NNLO for t-channel and W t production modes [35]. The detector response for each MC sample is simulated using a detailed GEANT4 [36] model of the ATLAS detector and subdetector-specific digitisation algorithms [37]. As the data are affected by the detector response to multiple pp interactions occurring in the same or in neighbouring bunch crossings (referred to as pile-up), minimum-bias interactions generated with PYTHIA 6.425 (with a specific LHC tune [38]) are overlaid on the generated signal and background events. The resulting events are re-weighted so that the distribution of the number of minimum-bias interactions per bunch crossing agrees with data. All samples are simulated with more than twice the effective luminosity of the data, except W + jets, where an equivalent of approximately 1.5 fb−1 is simulated. 3. Physics object reconstruction Muon candidates are reconstructed by combining an inner detector track with a track from the muon spectrometer. They are. 243. required to have p T > 10 GeV and |η| < 2.5.1 Muon quality criteria are applied in order to achieve a precise measurement of the muon momentum and reduce the misidentification rate [39]. These quality requirements correspond to a muon reconstruction and identification efficiency of approximately 95%. Electrons are reconstructed by matching clustered energy deposits in the EM calorimeter to tracks reconstructed in the inner detector [40]. The electron candidates are required to have p T > 15 GeV and to be within the fiducial volume of the inner detector, |η| < 2.47. The transition region between the barrel and end-cap EM calorimeters, with 1.37 < |η| < 1.52, is excluded. The candidates are required to pass quality criteria based on the expected calorimeter shower shape and amount of radiation in the transition radiation tracker. These quality requirements correspond to an electron identification (ID) efficiency of approximately 90%. Electrons and muons are considered isolated if they are away from large deposits of energy in the calorimeter, or tracks with large p T consistent with originating from the same vertex.2 In the τe τhad channel, isolated electrons are also required to pass a tighter identification requirement corresponding to an efficiency of approximately 80%. Jets are reconstructed using the anti-kt algorithm [41,42] with a radius parameter value of 0.4. The algorithm uses reconstructed, noise-suppressed clusters of calorimeter cells [43]. Jets are calibrated to the hadronic energy scale with correction factors based on simulation and validated using test-beam and collision data [44]. All jets are required to have p T > 25 GeV and |η| < 4.5. For jets within the inner detector acceptance (|η| < 2.4), the jet vertex fraction is required to be at least 0.75; the jet vertex fraction is defined as the sum of the p T of tracks associated with the jet and consistent with originating from the selected primary vertex, divided by the sum of the p T of all tracks associated with the jet. This requirement reduces the number of jets that originate from pile-up or are heavily contaminated by it. Events are discarded if a jet is associated with out-of-time activity or calorimeter noise [45]. Candidates for hadronic tau decays are defined as jets with either one or three associated tracks reconstructed in the inner detector. The kinematic properties of the tau candidate are reconstructed from the visible tau lepton decay products (all products excluding neutrinos). The tau charge is reconstructed from the sum of the charges of the associated tracks and is required to be ±1. The charge misidentification probability is found to be negligible. Hadronic tau decays are identified with a multivariate algorithm that employs boosted decision trees (BDTs) to discriminate against quark- and gluon-initiated jets using shower shape and tracking information [46]. Working points with a tau identification efficiency of about 50% (medium) for the τμ τhad and τe τhad channels and 60% (loose) for the τhad τhad channel are chosen, leading to a rate of false identification for quark- and gluon-initiated jets of a few percent [47]. Tau candidates are also required to have p T > 35 GeV and to be in the fiducial volume of the inner detector, |η| < 2.47. 1 ATLAS uses a right-handed coordinate system with its origin at the nominal interaction point (IP) in the centre of the detector and the z-axis along the beam pipe. The x-axis points from the IP to the centre of the LHC ring, and the y-axis points upward. Cylindrical coordinates (r , φ) are used in the transverse plane, φ being the azimuthal angle around the beam pipe. The pseudorapidity is defined in terms of the polar angle θ as η = − ln tan(θ/2). Separation in the η–φ plane is defined as R = (η)2 + (φ)2 . 2 Lepton isolation is defined using the sum of the E T deposited in calorimeter. cells within R < 0.2 of the lepton, E T0.2 , and the scalar sum of the p T of tracks with p T > 0.5 GeV consistent with the same vertex as the lepton and within R < 0.4, p 0T.4 . Muons are considered isolated if they have E T0.2 / p T < 4% (and p 0T.4 / p T < 6% in the. τe τμ channel). Isolated electrons must have p 0T.4 / p T < 5% and E T0.2 / p T <. 5% if p T < 100 GeV or E T0.2 < 5 GeV otherwise (E T0.2 / p T < 6% and p 0T.4 / p T < 8% in the τe τμ channel)..

(3) 244. ATLAS Collaboration / Physics Letters B 719 (2013) 242–260. (the EM calorimeter transition region is excluded). In the τlep τhad channels, tau candidates are required to have only one track, which must not be in the range |η| < 0.05, and to pass a muon veto. The removed pseudorapidity region corresponds to a gap in the transition radiation tracker that reduces the power of electron/pion discrimination. In the τe τhad channel, tau candidates are also required to pass an electron veto using BDTs. Geometric overlap of objects with R < 0.2 is resolved by selecting only one of the overlapping objects in the following order of priority: muons, electrons, tau candidates and jets. The missing transverse momentum (with magnitude E Tmiss ) is calculated from the vector sum of the transverse momenta of all high-p T objects reconstructed in the event, as well as a term for the remaining activity in the calorimeter [48]. Clusters associated with electrons, hadronic tau decays and jets are calibrated separately, with the remaining clusters calibrated at the EM energy scale. 4. Event selection Selected events in the τhad τhad channel must contain at least two oppositely-charged tau candidates with p T > 50 GeV and no electrons with p T > 15 GeV or muons with p T > 10 GeV. If the event was selected by the ditau trigger, both tau candidates are required to be geometrically matched to the objects that passed the trigger. For events that pass only the single-tau trigger there is no ambiguity, so trigger matching is not required. If multiple tau candidates are selected, the two highest-p T candidates are chosen. The angle between the tau candidates in the transverse plane must be greater than 2.7 radians. Selected events in the τlep τhad channels must contain exactly one isolated muon with p T > 25 GeV or an isolated electron with p T > 30 GeV; no additional electrons with p T > 15 GeV or muons with p T > 4 GeV; and exactly one tau candidate with p T > 35 GeV. The angle between the lepton and tau candidate in the transverse plane must be greater than 2.7 radians, and the pair must have opposite electric charge. For the τe τhad channel, the Z → ee and multijet contributions are reduced to a negligible level by requiring E Tmiss > 30 GeV. The W + jets background is suppressed by requiring the transverse mass, mT , of the electron–E Tmiss system, defined as. mT =. . 2p Te E Tmiss (1 − cos φ),. (1). where φ is the angle between the lepton and E Tmiss in the transverse plane, to be less than 50 GeV. Selected events in the τe τμ channel must contain exactly one isolated muon with p T > 25 GeV and one isolated electron with p T > 35 GeV and opposite electric charge, no additional electrons with p T > 15 GeV or muons with p T > 10 GeV and not more than one jet. The jet requirement suppresses t t̄ events, which typically have higher jet multiplicity than the signal. The two leptons are required to be back-to-back in the transverse plane using the criterion p vis ζ < 10 GeV, with. Te · ζ̂ + p Tμ · ζ̂ , p vis ζ =p. (2). where ζ̂ is a unit vector along the bisector of the e and μ momenta. This selection provides good suppression of the diboson and t t̄ backgrounds. For Z events, the E Tmiss tends to point away from the highest-p T lepton, so the angle between the highest-p T lepton and E Tmiss in the transverse plane is required to be greater than 2.6 radians. The search in all channels is performed by counting events in signal regions with total transverse mass above thresholds optimised separately for each signal mass hypothesis in each channel. Table 1 Thresholds on mtot T used for each signal mass point in each channel. All values are given in GeV. mZ. 500. 625. 750. 875. 1000. 1125. 1250. τhad τhad τμ τhad τe τhad τe τμ. 350 400 400 300. 400 400 400 350. 500 500 400 350. 500 500 500 350. 650 600 500 500. 650 600 500 500. 700 600 500 500. to give the best expected exclusion limits (see Table 1). The total transverse mass, mtot T , is defined as the mass of the visible decay. products of both tau leptons and E Tmiss , neglecting longitudinal momentum components and the tau lepton mass,. mtot T =. . 2p T1 p T2 C + 2E Tmiss p T1 C 1 + 2E Tmiss p T2 C 2 ,. (3). where p T1 and p T2 are the transverse momenta of the visible products of the two tau decays; C is defined as 1 − cos φ , where φ is the angle in the transverse plane between the visible products of the two tau decays; and C 1 and C 2 are defined analogously for the angles in the transverse plane between E Tmiss and the visible products of the first and second tau decay, respectively. Figs. 1(a)–1(d) show the mtot T distribution after event selection in each channel. 5. Background estimation The dominant background processes in the τhad τhad channel are multijet production and Z /γ ∗ → τ τ . Minor contributions come from W (→ τ ν )+ jets, Z (→ )+ jets ( = e or μ), W (→ ν )+ jets, t t̄, single top-quark and diboson production. The shape of the multijet mass distribution is estimated from data that pass the full event selection but have two tau candidates of the same electric charge. The contribution is normalised to events that pass the full event selection but have low mtot T . All other background contributions are estimated from simulation. The main background contributions in the τlep τhad channels come from Z /γ ∗ → τ τ , W + jets, t t̄ and diboson production, with minor contributions from Z (→ ) + jets, multijet and single topquark events. The contributions involving fake hadronic tau decays from multijet and W + jets events are modelled with data-driven techniques involving fake factors, which parameterise the rate for lepton candidates in jets to pass lepton isolation or jets to pass tau identification, respectively. The remaining background is estimated using simulation. The dominant background processes in the τe τμ channel are t t̄, Z /γ ∗ → τ τ and diboson production. Contributions from processes such as Z (→ μμ) + jets, W + jets and W γ + jets, where a jet or photon is misidentified as an electron, are very small in the signal region. Multijet events are suppressed by tight lepton isolation criteria. Since background processes involving fake leptons make only minor contributions, all background contributions in the τe τμ channel are estimated using simulation. The MC estimates of the dominant background contributions are checked using high-purity control regions in data. The following subsections describe the data-driven background estimates in more detail. 5.1. Multijet background in the τhad τhad channel The shape of the mtot T distribution for the multijet background is estimated using events that pass the standard event selection, but have two selected τhad candidates with the same electric tot charge and with mtot region T > 200 GeV to avoid the low mT which is affected by the tau p T threshold. For a low-mass signal with m Z 625 GeV, a lower bound of 160 GeV is used, as.

(4) ATLAS Collaboration / Physics Letters B 719 (2013) 242–260. 245. tot Fig. 1. The mtot T distribution after event selection without the mT requirement for each channel: (a) τhad τhad , (b) τμ τhad , (c) τe τhad and (d) τe τμ . The estimated contributions from SM processes are stacked and appear in the same order as in the legend. The contribution from Z → ee events in which an electron is misidentified as a tau candidate is shown separately in the τe τhad channel. A Z SSM signal and the events observed in data are overlaid. The signal mass point closest to the Z SSM exclusion limit in each channel is chosen and is indicated in parentheses in the legend in units of GeV. The uncertainty on the total estimated background (hatched) includes only the statistical uncertainty from the simulated samples. The visible decay products of hadronically decaying taus are denoted by τhad-vis .. discussed below. This control region has only 2% contamination from other background processes and negligible signal contamination. The mtot T distribution is modelled by performing an unbinned maximum likelihood fit to the data in the control region using the following function:. . . . . tot f mtot T p 0 , p 1 , p 2 = p 0 · mT. p 1 + p 2 log(mtot T ). ,. (4). where p 0 , p 1 and p 2 are free parameters. The integral of the fitted function in the high-mass tail matches the number of observed events well for any choice of the mtot T threshold, and the function models the high-mass tail well in a simulated dijet sample enriched in high-mass events. The statistical uncertainty is estimated using pseudo-experiments and increases monotonically from 12% to 83% with increasing mtot T threshold. The systematic uncertainty due to the choice of the fitting function is evaluated using alternative fitting functions and ranges from 1% to 7%. The multijet model is normalised to data that pass all analysis requirements but have mtot T in the range 200–250 GeV. For the low-mass points with m Z 625 GeV, the low-mtot T side-band is lowered to 160– 200 GeV to keep signal contamination negligible. Both side-bands have a maximum contamination of 5% from other background processes, which is subtracted, and negligible contamination from signal. The statistical uncertainty from the normalisation ranges from 2% to 5%. Systematic uncertainties affecting the normalisation of the background processes are propagated when performing the subtraction but have a negligible effect.. 5.2. Multijet background in the τlep τhad channels The background from multijet events is negligible at high mtot T , but it is important to estimate its contribution to model the inclusive mass distribution. Multijet events are exceptional among the background processes because the muons and electrons produced in heavy-flavour decays or the light-flavour hadrons falsely identified as electrons, are typically not isolated in the calorimeter but produced in jets. To estimate the multijet background, events in the data that fail lepton isolation are weighted event-by-event, with fake factors for lepton isolation measured from data in a multijet-rich control region (multijet-CR). The multijet-CR is defined by requiring exactly one selected lepton, as in Section 4, but without the isolation requirement; at least one tau candidate that fails the BDT ID; no tau candidates that pass the BDT ID; E Tmiss < 15 GeV for the τμ τhad channel, E Tmiss < 30 GeV for the τe τhad channel; and the transverse mass formed by the lepton and E Tmiss , mT ( , E Tmiss ), to be less than 30 GeV. For the τμ τhad channel, where the multijet contribution is dominated by b-quark-initiated jets, the muon is additionally required to have a transverse impact parameter of |d0 (μ)| > 0.08 mm with respect to the primary vertex, which increases the purity of the multijet control region. The leptons in the multijet control region are divided into those that pass (isolated) and a subset that fail (anti-isolated) the isolation requirements. In the τμ τhad channel the anti-isolated sample includes all muons that fail isolation, while in the τe τhad channel, the anti-isolation requirement is tightened to reduce contamination from real isolated electrons. Isolation fake factors, f iso , are.

(5) 246. ATLAS Collaboration / Physics Letters B 719 (2013) 242–260. defined as the number of isolated leptons in the data, N iso , divided by the number of anti-isolated leptons, N anti-iso , binned in p T and η :. f iso ( p T , η) ≡. . N anti-iso ( p T , η) multijet-CR N iso ( p T , η) . (5). Contamination from real isolated leptons is estimated using simulation and subtracted from N iso (∼3% for τμ τhad and ∼25% for τe τhad ). The number of multijet events passing lepton isolation, N multijet , is predicted by weighting the events with anti-isolated leptons by their fake factor:. N multijet ( p T , η, x). anti-iso anti-iso ( p T , η, x) − N MC ( p T , η, x) . = f iso ( p T , η) N data. (6). The shape of the multijet background in a given kinematic variable, x, is modelled from the events in the data with anti-isolated lepanti-iso tons, N data , corrected by subtracting the expected contamination from other background processes predicted with MC simulation, anti-iso N MC . This method assumes that the ratio of the number of isolated leptons to the number of anti-isolated leptons in multijet events is not strongly correlated with the requirements used to enrich the multijet control sample. This assumption has been verified by varying the E Tmiss and d0 selection criteria used to define the multijet control region. A conservative 100% systematic uncertainty on the isolation fake factor is assumed, but this has negligible effect on the sensitivity because the expected multijet background is less than a percent of the total background in both the τμ τhad and τe τhad channels. 5.3. W + jets background in the τlep τhad channels The W + jets background is estimated using a technique similar to the multijet estimate, where tau candidates that fail the BDT ID are weighted event-by-event with fake factors for jets to pass the BDT ID in W + jets events. A high purity W + jets control region (W-CR) is defined by selecting events that have exactly one isolated lepton, as in Section 4; at least one tau candidate that is not required to pass the BDT ID; and mT ( , E Tmiss ) between 70 and 200 GeV. For the τe τhad channel, the tau candidate is additionally required to pass the electron veto. Tau ID fake factors, f τ , are defined as the number of tau candidates that pass the BDT ID, N pass τ -ID , divided by the number that fail, N fail τ -ID , binned in p T and η :. f τ ( p T , η) ≡ . N fail τ -ID ( p T , η) W-CR N pass τ -ID ( p T , η) . (7). The number of W + jets events passing the BDT ID, N W +jets , is predicted by weighting the events that fail the BDT ID by their fake factor:. . fail τ -ID N W +jets ( p T , η, x) = f τ ( p T , η) N data ( p T , η, x). fail τ -ID fail τ -ID ( p T , η, x) − N MC ( p T , η, x) . − N multijet. (8). The shape of the W + jets background is modelled using events in fail τ -ID the data that failed the BDT ID, N data , with the multijet contam-. fail τ -ID ination, N multijet (estimated from data), and other contamination,. fail τ -ID N MC (estimated from simulation), subtracted. A 30% systematic uncertainty on the fake factors is assigned by comparing the fake factors to those measured in a data sample enriched in Z + jets instead of W + jets, which provides a sample of jets with a similar quark/gluon fraction [49]. This background estimation method relies on the assumption that the tau identification. fake factors for W + jets events are not strongly correlated with the selection used to define the W + jets control region. This assumption has been verified by varying the mT selection criterion used to define the W + jets control region, resulting in a few percent variation, which is well within the systematic uncertainty. 6. Systematic uncertainties Systematic effects on the contributions of signal and background processes estimated from simulation are discussed in this section. These include theoretical uncertainties on the cross sections of simulated processes and experimental uncertainties on the trigger, reconstruction and identification efficiencies; on the energy and momentum scales and resolutions; and on the measurement of the integrated luminosity. For each source of uncertainty, the correlations across analysis channels, as well as the correlations between signal and background, are taken into account. Uncertainties on the background contributions estimated from data have been discussed in their respective sections. The overall uncertainty on the Z signal and the Z /γ ∗ → τ τ background due to PDFs, α S and scale variations is estimated to be 12% at 1.5 TeV, dominated by the PDF uncertainty [12]. The uncertainty is evaluated using PDF error sets, and the spread of the variations covers the difference between the central values obtained with the CTEQ and MSTW PDF sets. Additionally, for Z /γ ∗ → τ τ , a systematic uncertainty of 10% is attributed to electroweak corrections [50]. This uncertainty is not considered for the signal as it is strongly model-dependent. An uncertainty of 4–5% is assumed for the inclusive cross section of the single gauge boson and diboson production mechanisms and a relative uncertainty of 24% is added in quadrature per additional jet, due to the irreducible Berends-scaling uncertainty [51,52]. For t t̄ and single top-quark production, the QCD scale uncertainties are in the range of 3–6% [35,53,54]. The uncertainties related to the proton PDFs, including those arising from the choice of PDF set, amount to 8% for the predominantly gluon-initiated processes such as t t̄ and 4% for the predominantly quark-initiated processes at low mass, such as onshell single gauge boson and diboson production [25,28,55–57]. The uncertainty on the integrated luminosity is 3.9% [58,59]. The efficiencies of the electron, muon and hadronic tau triggers are measured in data and are used to correct the simulation. The associated systematic uncertainties are typically 1–2% for electrons and muons, 2.5% for the ditau trigger and 5% for the high-p T single-tau trigger. Differences between data and simulation in the reconstruction and identification efficiencies of electrons, muons, and hadronic tau decays are taken into account, as well as the differences in the energy and momentum scales and resolutions. The associated uncertainties for muons and electrons are typically < 1%. The systematic uncertainties on the identification efficiency of hadronic tau decays are estimated at low p T from data samples enriched in W → τ ν and Z → τ τ events. At high p T , there are no abundant sources of real hadronic tau decays to make an efficiency measurement. Rather, the fraction of jets that pass the tau identification is studied in high-p T dijet events as a function of the jet p T , which indicates that there is no degradation in the modelling of the detector response as a function of the p T of tau candidates. From these studies, an efficiency uncertainty of up to 8% is assigned to high-p T tau candidates. The uncertainty on the jet-to-tau misidentification rate is 50%, determined from data-MC comparisons in W + jet events. The uncertainty on the electron-to-tau misidentification rate is 50–100%, depending on the pseudorapidity of the tau candidate, based on measurements made using a Z → ee sample selected from data [47]. The energy scale uncertainty on taus and jets is evaluated based on the single-hadron response in.

(6) ATLAS Collaboration / Physics Letters B 719 (2013) 242–260. Table 2 Uncertainties on the estimated signal and total background contributions in percent for each channel. The following signal masses, chosen to be close to the region where the limits are set, are used: 1250 GeV for τhad τhad (hh); 1000 GeV for τμ τhad (μh) and τe τhad (eh); and 750 GeV for τe τμ (e μ). A dash denotes that the uncertainty is not applicable. The statistical uncertainty corresponds to the uncertainty due to limited sample size in the MC and control regions. Uncertainty [%]. Stat. uncertainty Eff. and fake rate Energy scale and res. Theory cross section Luminosity Data-driven methods. Signal. Background. hh. μh. eh. eμ. 1 16 5 8 4 –. 2 10 7 6 4 –. 2 8 6 6 4 –. 3 1 2 5 4 –. hh 5 12. +22 −11. 9 2. +21 −11. μh. eh. eμ. 20 16 3 4 2 6. 23 4 8 4 2 16. 7 3 5 5 4 –. the calorimeters [44,60]. In addition, the tau energy scale is validated in data samples enriched in Z → τ τ events. The systematic uncertainties related to the jet and tau energy scale and resolution are functions of η and p T , and are generally near 3%. These uncertainties are treated as fully correlated. Energy scale and resolution uncertainties on all objects are propagated to the E Tmiss calculation.. The uncertainty on the E Tmiss due to clusters that do not belong to any reconstructed object is measured to be negligible in all channels. Table 2 summarises the uncertainties on the estimated signal and total background contributions in each channel. For the background, the contribution from each uncertainty depends on the fraction of the background estimated with simulation. The dominant uncertainties on the background come from the multijet shape estimation and the tau energy scale uncertainty for Z /γ ∗ → τ τ events in the τhad τhad channel, from the limited sample size and the fake factor estimate of the W + jets background in the τlep τhad channels and from the statistical uncertainty of the MC samples in the τe τμ channel. The dominant uncertainty on the signal for the τhad τhad and τlep τhad channels comes from the tau identification efficiency and for the τe τμ channel, from the statistical uncertainty on the MC samples.. 247. fore, upper limits are set on the production of a high-mass resonance decaying to τ + τ − pairs. The statistical combination of the channels employs a likelihood function constructed as the product of Poisson probability terms describing the total number of events observed in each channel. The Poisson probability in each channel is evaluated for the observed number of data events given the signal plus background expectation. Systematic uncertainties on the expected number of events are incorporated into the likelihood via Gaussian-distributed nuisance parameters. Correlations across channels are taken into account. A signal strength parameter multiplies the expected signal in each channel, for which a positive uniform prior probability distribution is assumed. Theoretical uncertainties on the signal cross section are not included in the calculation of the experimental limit as they are model-dependent. Bayesian 95% credibility upper limits are set on the cross section times branching fraction for a high-mass resonance decaying into a τ + τ − pair as a function of the resonance mass, using the Bayesian Analysis Toolkit [61]. Figs. 2(a) and 2(b) show the limits for the individual channels and for the combination, respectively. The resulting 95% credibility lower limit on the mass of a Z SSM decaying to τ + τ − pairs is 1.40 TeV, with an expected limit of 1.42 TeV. The observed and expected limits in the individual channels are, respectively: 1.26 and 1.35 TeV (τhad τhad ); 1.07 and 1.06 TeV (τμ τhad ); 1.10 and 1.03 TeV (τe τhad ); and 0.72 and 0.82 TeV (τe τμ ). The impact of the choice of the prior on the signal strength parameter has been evaluated by also considering the reference prior [62]. Use of the reference prior improves the mass limits by approximately 50 GeV. The impact of the vector and axial coupling strengths of the Z has been investigated, as these can alter the fraction of the tau momentum carried by the visible decay products. For purely V − A couplings, the limit on the cross section times τ + τ − branching fraction is improved by ∼10% over the mass range. For purely V + A couplings, there is a mass-dependent degradation, from ∼15% at high mass to ∼40% at low mass. All variations lie within the 1σ band of the expected exclusion limit. 8. Conclusion. 7. Results and discussion The numbers of observed and expected events including their total uncertainties, after the full selection in all channels, are summarised in Table 3. In all cases, the number of observed events is consistent with the expected Standard Model background. There-. A search for high-mass ditau resonances has been performed 1 using 4.6 fb−√ of data collected with the ATLAS detector in pp collisions at s = 7 TeV at the LHC. The τhad τhad , τμ τhad , τe τhad and τe τμ channels are analysed. The observed number of events in the high-transverse-mass region is consistent with the SM expec-. Table 3 Number of expected and observed events after event selection for each analysis channel. The expected contribution from the signal and background in each channel is calculated for the signal mass point closest to the Z SSM exclusion limit. The total uncertainties on each estimated contribution are shown. The signal efficiency denotes the expected number of signal events divided by the product of the production cross section, the ditau branching fraction and the integrated luminosity, σ ( pp → Z SSM )× BR( Z SSM → τ τ ) × L dt.. τhad τhad. τμ τhad. τe τhad. τe τμ. m Z [GeV] mtot T threshold [GeV]. 1250 700. 1000 600. 1000 500. 750 350. Z /γ ∗ → τ τ W + jets Z (→ ) + jets t t̄ Diboson Single top Multijet. 0.73 ± 0.23 < 0.03 < 0.01 < 0.02 < 0.01 < 0.01 0.24 ± 0.15. 0.36 ± 0.06 0.28 ± 0.22 < 0.1 0.33 ± 0.15 0.23 ± 0.07 0.19 ± 0.18 < 0.01. 0.57 ± 0.11 0.8 ± 0 .4 < 0.01 0.13 ± 0.09 0.06 ± 0.03 < 0.1 < 0.1. 0.55 ± 0.07 0.33 ± 0.10 0.06 ± 0.02 0.97 ± 0.22 1.69 ± 0.24 < 0.1 < 0.01. Total expected background Events observed. 0.97 ± 0.27 2. 1.4 ± 0.4 1. 1.6 ± 0.5 0. 3.6 ± 0.4 5. Expected signal events Signal efficiency (%). 6.3 ± 1.1 4.3. 5.5 ± 0.7 1.1. 5.0 ± 0.5 1.0. 6.72 ± 0.26 0.4.

(7) 248. ATLAS Collaboration / Physics Letters B 719 (2013) 242–260. Fig. 2. (a) The expected (dashed) and observed (solid) 95% credibility upper limits on the cross section times τ + τ − branching fraction, in the τhad τhad , τμ τhad , τe τhad and τe τμ channels and for the combination. The expected Z SSM production cross section and its corresponding theoretical uncertainty (dotted) are also included. (b) The expected and observed limits for the combination including 1σ and 2σ uncertainty bands. Z SSM masses up to 1.40 TeV are excluded, in agreement with the expected limit of 1.42 TeV in the absence of a signal.. tation. Limits are set on the cross section times branching fraction for such resonances. The resulting lower limit on the mass of a Z decaying to τ + τ − in the Sequential Standard Model is 1.40 TeV at 95% credibility, in agreement with the expected limit of 1.42 TeV in the absence of a signal. Acknowledgements We thank CERN for the very successful operation of the LHC, as well as the support staff from our institutions without whom ATLAS could not be operated efficiently. We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWF and FWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; CONICYT, Chile; CAS, MOST and NSFC, China; COLCIENCIAS, Colombia; MSMT CR, MPO CR and VSC CR, Czech Republic; DNRF, DNSRC and Lundbeck Foundation, Denmark; EPLANET and ERC, European Union; IN2P3-CNRS, CEA-DSM/IRFU, France; GNSF, Georgia; BMBF, DFG, HGF, MPG and AvH Foundation, Germany; GSRT, Greece; ISF, MINERVA, GIF, DIP and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; FOM and NWO, Netherlands; BRF and RCN, Norway; MNiSW, Poland; GRICES and FCT, Portugal; MERYS (MECTS), Romania; MES of Russia and ROSATOM, Russian Federation; JINR; MSTD, Serbia; MSSR, Slovakia; ARRS and MVZT, Slovenia; DST/NRF, South Africa; MICINN, Spain; SRC and Wallenberg Foundation, Sweden; SER, SNSF and Cantons of Bern and Geneva, Switzerland; NSC, Taiwan; TAEK, Turkey; STFC, the Royal Society and Leverhulme Trust, United Kingdom; DOE and NSF, United States of America. The crucial computing support from all WLCG partners is acknowledged gratefully, in particular from CERN and the ATLAS Tier-1 facilities at TRIUMF (Canada), NDGF (Denmark, Norway, Sweden), CC-IN2P3 (France), KIT/GridKA (Germany), INFN-CNAF (Italy), NL-T1 (Netherlands), PIC (Spain), ASGC (Taiwan), RAL (UK) and BNL (USA) and in the Tier-2 facilities worldwide. Open access This article is published Open Access at sciencedirect.com. It is distributed under the terms of the Creative Commons Attribution License 3.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are credited.. References [1] P. Langacker, Rev. Mod. Phys. 81 (2009) 1199, arXiv:0801.1345 [hep-ph]. [2] J.L. Hewett, et al., Phys. Rep. 183 (1989) 193. [3] M. Cvetic, et al., Discovery and identification of extra gauge bosons, arXiv: hep-ph/9504216, 1995. [4] A. Leike, Phys. Rep. 317 (1999) 143, arXiv:hep-ph/9805494. [5] T.G. Rizzo, Z phenomenology and the LHC, arXiv:hep-ph/0610104, 2006. [6] R. Diener, et al., Phys. Rev. D 83 (2011) 115008, arXiv:1006.2845 [hep-ph]. [7] K.R. Lynch, et al., Phys. Rev. D 63 (2001) 035006, arXiv:hep-ph/0007286. [8] ATLAS Collaboration, JINST 3 (2008) S08003. [9] CDF Collaboration, D. Acosta, et al., Phys. Rev. Lett. 95 (2005) 131801, arXiv: hep-ex/0506034. [10] CMS Collaboration, Phys. Lett. B 716 (2012) 82, arXiv:1206.1725 [hep-ex]. [11] R.S. Chivukula, et al., Phys. Rev. D 66 (2002) 015006, arXiv:hep-ph/0205064. [12] ATLAS Collaboration, JHEP 1211 (2012) 138, arXiv:1209.2535 [hep-ex]. [13] CMS Collaboration, Phys. Lett. B 714 (2012) 158, arXiv:1206.1849 [hep-ex]. [14] L.R. Evans, et al., JINST 3 (2008) S08001. [15] M.L. Mangano, et al., JHEP 0307 (2003) 001, arXiv:hep-ph/0206293. [16] S. Frixione, et al., JHEP 0206 (2002) 029, arXiv:hep-ph/0204244. [17] S. Frixione, et al., JHEP 0807 (2008) 029, arXiv:0805.3067 [hep-ph]. [18] G. Corcella, et al., JHEP 0101 (2001) 010, arXiv:hep-ph/0011363. [19] J.M. Butterworth, et al., Z. Phys. C 72 (1996) 637, arXiv:hep-ph/9601371. [20] B.P. Kersevan, et al., The Monte Carlo event generator AcerMC version 2.0 with interfaces to PYTHIA 6.2 and HERWIG 6.5, arXiv:hep-ph/0405247, 2004. [21] T. Sjöstrand, et al., JHEP 0605 (2006) 026, arXiv:hep-ph/0603175. [22] P. Golonka, et al., Eur. Phys. J. C 45 (2006) 97, arXiv:hep-ph/0506026. [23] N. Davidson, et al., Comput. Phys. Commun. 183 (2012) 821, arXiv:1002.0543 [hep-ph]. [24] J. Pumplin, et al., JHEP 0207 (2002) 012, arXiv:hep-ph/0201195. [25] H.-L. Lai, et al., Phys. Rev. D 82 (2010) 074024, arXiv:1007.2241 [hep-ph]. [26] A. Sherstnev, et al., Eur. Phys. J. C 55 (2008) 553, arXiv:0711.2473 [hep-ph]. [27] R. Hamberg, et al., Nucl. Phys. B 359 (1991) 343. [28] A.D. Martin, et al., Eur. Phys. J. C 63 (2009) 189, arXiv:0901.0002 [hep-ph]. [29] K. Melnikov, et al., Phys. Rev. D 74 (2006) 114017. [30] R. Gavin, et al., Comput. Phys. Commun. 182 (2011) 2388, arXiv:1011.3540 [hep-ph]. [31] S. Moch, et al., Phys. Rev. D 78 (2008) 034003. [32] U. Langenfeld, et al., New results for t t̄ production at hadron colliders, arXiv: 0907.2527 [hep-ph], 2009. [33] M. Aliev, et al., Comput. Phys. Commun. 182 (2011) 1034, arXiv:1007.1327 [hep-ph]. [34] N. Kidonakis, Phys. Rev. D 81 (2010) 054028, arXiv:1001.5034 [hep-ph]. [35] N. Kidonakis, Phys. Rev. D 83 (2011) 091503, arXiv:1103.2792 [hep-ph]. [36] S. Agostinelli, et al., Nucl. Instrum. Meth. A 506 (2003) 250. [37] ATLAS Collaboration, Eur. Phys. J. C 70 (2010) 823, arXiv:1005.4568 [physics.ins-det]. [38] ATLAS Collaboration, ATLAS tunes of PYTHIA 6 and PYTHIA 8 for MC11, ATLPHYS-PUB-2011-009, 2011, http://cdsweb.cern.ch/record/1363300. [39] ATLAS Collaboration, Muon reconstruction efficiency in reprocessed 2010 LHC proton–proton collision data recorded with the ATLAS detector, ATLAS-CONF2011-063, 2011, http://cdsweb.cern.ch/record/1345743. [40] ATLAS Collaboration, Eur. Phys. J. C 72 (2012) 1909, arXiv:1110.3174 [hep-ex]. [41] M. Cacciari, et al., JHEP 0804 (2008) 063, arXiv:0802.1189 [hep-ph]..

(8) ATLAS Collaboration / Physics Letters B 719 (2013) 242–260. [42] M. Cacciari, et al., Phys. Lett. B 641 (2006) 57, arXiv:hep-ph/0512210. [43] W. Lampl, et al., Calorimeter clustering algorithms: Description and performance, ATL-LARG-PUB-2008-002, 2008, http://cdsweb.cern.ch/record/1099735. [44] ATLAS Collaboration, Eur. Phys. J. C, in press, arXiv:1112.6426 [hep-ex]. [45] ATLAS Collaboration, Data-quality requirements and event cleaning for jets and missing transverse energy reconstruction with the ATLAS detector in proton– √ proton collisions at a center-of-mass energy of s = 7 TeV, ATLAS-CONF-2010038, 2010, http://cdsweb.cern.ch/record/1277678. [46] ATLAS Collaboration, Reconstruction, energy calibration, and identification of hadronically decaying tau leptons, ATLAS-CONF-2011-077, 2011, http:// cdsweb.cern.ch/record/1353226. [47] ATLAS Collaboration, Performance of the reconstruction and identification of hadronic tau decays with ATLAS, ATLAS-CONF-2011-152, 2011, http:// cdsweb.cern.ch/record/1398195. [48] ATLAS Collaboration, Eur. Phys. J. C 72 (2012) 1844, arXiv:1108.5602 [hep-ex]. [49] J. Gallicchio, et al., JHEP 1110 (2011) 103, arXiv:1104.1175 [hep-ph]. [50] ATLAS Collaboration, Phys. Rev. Lett. 107 (2011) 272002, arXiv:1108.1582 [hep-ex]. [51] F.A. Berends, et al., Phys. Lett. B 224 (1989) 237.. [52] [53] [54] [55] [56] [57] [58]. [59] [60]. [61] [62]. 249. F.A. Berends, et al., Nucl. Phys. B 357 (1991) 32. S. Moch, et al., Phys. Rev. D 78 (2008) 034003, arXiv:0804.1476 [hep-ph]. M. Beneke, et al., Phys. Lett. B 690 (2010) 483, arXiv:0911.5166 [hep-ph]. M. Botje, et al., The PDF4LHC Working Group interim recommendations, arXiv: 1101.0538 [hep-ph], 2011. S. Alekhin, et al., The PDF4LHC Working Group interim report, arXiv:1101.0536 [hep-ph], 2011. R.D. Ball, et al., Nucl. Phys. B 849 (2011) 296, arXiv:1101.1300 [hep-ph]. √ ATLAS Collaboration, Luminosity determination in pp collisions at s = 7 TeV using the ATLAS detector in 2011, ATLAS-CONF-2011-116, 2011, http:// cdsweb.cern.ch/record/1376384. ATLAS Collaboration, Eur. Phys. J. C 71 (2011) 1630, arXiv:1101.2185 [hep-ex]. ATLAS Collaboration, Determination of the tau energy scale and the associ√ ated systematic uncertainty in proton–proton collisions at s = 7 TeV with the ATLAS detector at the LHC in 2011, ATLAS-CONF-2012-054, 2012, http:// cdsweb.cern.ch/record/1453781. A. Caldwell, et al., Comput. Phys. Commun. 180 (2009) 2197, arXiv:0808.2552 [physics.data-an]. D. Casadei, JINST 7 (2012) 1012, arXiv:1108.4270 [physics.data-an].. ATLAS Collaboration. G. Aad 48 , T. Abajyan 21 , B. Abbott 111 , J. Abdallah 12 , S. Abdel Khalek 115 , A.A. Abdelalim 49 , O. Abdinov 11 , R. Aben 105 , B. Abi 112 , M. Abolins 88 , O.S. AbouZeid 158 , H. Abramowicz 153 , H. Abreu 136 , B.S. Acharya 164a,164b , L. Adamczyk 38 , D.L. Adams 25 , T.N. Addy 56 , J. Adelman 176 , S. Adomeit 98 , P. Adragna 75 , T. Adye 129 , S. Aefsky 23 , J.A. Aguilar-Saavedra 124b,a , M. Agustoni 17 , M. Aharrouche 81 , S.P. Ahlen 22 , F. Ahles 48 , A. Ahmad 148 , M. Ahsan 41 , G. Aielli 133a,133b , T.P.A. Åkesson 79 , G. Akimoto 155 , A.V. Akimov 94 , M.S. Alam 2 , M.A. Alam 76 , J. Albert 169 , S. Albrand 55 , M. Aleksa 30 , I.N. Aleksandrov 64 , F. Alessandria 89a , C. Alexa 26a , G. Alexander 153 , G. Alexandre 49 , T. Alexopoulos 10 , M. Alhroob 164a,164c , M. Aliev 16 , G. Alimonti 89a , J. Alison 120 , B.M.M. Allbrooke 18 , P.P. Allport 73 , S.E. Allwood-Spiers 53 , J. Almond 82 , A. Aloisio 102a,102b , R. Alon 172 , A. Alonso 79 , F. Alonso 70 , A. Altheimer 35 , B. Alvarez Gonzalez 88 , M.G. Alviggi 102a,102b , K. Amako 65 , C. Amelung 23 , V.V. Ammosov 128,∗ , S.P. Amor Dos Santos 124a , A. Amorim 124a,b , N. Amram 153 , C. Anastopoulos 30 , L.S. Ancu 17 , N. Andari 115 , T. Andeen 35 , C.F. Anders 58b , G. Anders 58a , K.J. Anderson 31 , A. Andreazza 89a,89b , V. Andrei 58a , M.-L. Andrieux 55 , X.S. Anduaga 70 , S. Angelidakis 9 , P. Anger 44 , A. Angerami 35 , F. Anghinolfi 30 , A. Anisenkov 107 , N. Anjos 124a , A. Annovi 47 , A. Antonaki 9 , M. Antonelli 47 , A. Antonov 96 , J. Antos 144b , F. Anulli 132a , M. Aoki 101 , S. Aoun 83 , L. Aperio Bella 5 , R. Apolle 118,c , G. Arabidze 88 , I. Aracena 143 , Y. Arai 65 , A.T.H. Arce 45 , S. Arfaoui 148 , J.-F. Arguin 93 , S. Argyropoulos 42 , E. Arik 19a,∗ , M. Arik 19a , A.J. Armbruster 87 , O. Arnaez 81 , V. Arnal 80 , C. Arnault 115 , A. Artamonov 95 , G. Artoni 132a,132b , D. Arutinov 21 , S. Asai 155 , S. Ask 28 , B. Åsman 146a,146b , L. Asquith 6 , K. Assamagan 25,d , A. Astbury 169 , M. Atkinson 165 , B. Aubert 5 , E. Auge 115 , K. Augsten 127 , M. Aurousseau 145a , G. Avolio 30 , R. Avramidou 10 , D. Axen 168 , G. Azuelos 93,e , Y. Azuma 155 , M.A. Baak 30 , G. Baccaglioni 89a , C. Bacci 134a,134b , A.M. Bach 15 , H. Bachacou 136 , K. Bachas 30 , M. Backes 49 , M. Backhaus 21 , J. Backus Mayes 143 , E. Badescu 26a , P. Bagnaia 132a,132b , S. Bahinipati 3 , Y. Bai 33a , D.C. Bailey 158 , T. Bain 158 , J.T. Baines 129 , O.K. Baker 176 , M.D. Baker 25 , S. Baker 77 , P. Balek 126 , E. Banas 39 , P. Banerjee 93 , Sw. Banerjee 173 , D. Banfi 30 , A. Bangert 150 , V. Bansal 169 , H.S. Bansil 18 , L. Barak 172 , S.P. Baranov 94 , A. Barbaro Galtieri 15 , T. Barber 48 , E.L. Barberio 86 , D. Barberis 50a,50b , M. Barbero 21 , D.Y. Bardin 64 , T. Barillari 99 , M. Barisonzi 175 , T. Barklow 143 , N. Barlow 28 , B.M. Barnett 129 , R.M. Barnett 15 , A. Baroncelli 134a , G. Barone 49 , A.J. Barr 118 , F. Barreiro 80 , J. Barreiro Guimarães da Costa 57 , P. Barrillon 115 , R. Bartoldus 143 , A.E. Barton 71 , V. Bartsch 149 , A. Basye 165 , R.L. Bates 53 , L. Batkova 144a , J.R. Batley 28 , A. Battaglia 17 , M. Battistin 30 , F. Bauer 136 , H.S. Bawa 143,f , S. Beale 98 , T. Beau 78 , P.H. Beauchemin 161 , R. Beccherle 50a , P. Bechtle 21 , H.P. Beck 17 , A.K. Becker 175 , S. Becker 98 , M. Beckingham 138 , K.H. Becks 175 , A.J. Beddall 19c , A. Beddall 19c , S. Bedikian 176 , V.A. Bednyakov 64 , C.P. Bee 83 , L.J. Beemster 105 , M. Begel 25 , S. Behar Harpaz 152 , P.K. Behera 62 , M. Beimforde 99 , C. Belanger-Champagne 85 , P.J. Bell 49 , W.H. Bell 49 , G. Bella 153 , L. Bellagamba 20a , M. Bellomo 30 , A. Belloni 57 , O. Beloborodova 107,g , K. Belotskiy 96 , O. Beltramello 30 , O. Benary 153 , D. Benchekroun 135a , K. Bendtz 146a,146b , N. Benekos 165 , Y. Benhammou 153 , E. Benhar Noccioli 49 , J.A. Benitez Garcia 159b , D.P. Benjamin 45 , M. Benoit 115 , J.R. Bensinger 23 , K. Benslama 130 , S. Bentvelsen 105 , D. Berge 30 , E. Bergeaas Kuutmann 42 , N. Berger 5 , F. Berghaus 169 ,.

(9) 250. ATLAS Collaboration / Physics Letters B 719 (2013) 242–260. E. Berglund 105 , J. Beringer 15 , P. Bernat 77 , R. Bernhard 48 , C. Bernius 25 , T. Berry 76 , C. Bertella 83 , A. Bertin 20a,20b , F. Bertolucci 122a,122b , M.I. Besana 89a,89b , G.J. Besjes 104 , N. Besson 136 , S. Bethke 99 , W. Bhimji 46 , R.M. Bianchi 30 , L. Bianchini 23 , M. Bianco 72a,72b , O. Biebel 98 , S.P. Bieniek 77 , K. Bierwagen 54 , J. Biesiada 15 , M. Biglietti 134a , H. Bilokon 47 , M. Bindi 20a,20b , S. Binet 115 , A. Bingul 19c , C. Bini 132a,132b , C. Biscarat 178 , B. Bittner 99 , C.W. Black 150 , K.M. Black 22 , R.E. Blair 6 , J.-B. Blanchard 136 , G. Blanchot 30 , T. Blazek 144a , I. Bloch 42 , C. Blocker 23 , J. Blocki 39 , A. Blondel 49 , W. Blum 81 , U. Blumenschein 54 , G.J. Bobbink 105 , V.S. Bobrovnikov 107 , S.S. Bocchetta 79 , A. Bocci 45 , C.R. Boddy 118 , M. Boehler 48 , J. Boek 175 , N. Boelaert 36 , J.A. Bogaerts 30 , A. Bogdanchikov 107 , A. Bogouch 90,∗ , C. Bohm 146a , J. Bohm 125 , V. Boisvert 76 , T. Bold 38 , V. Boldea 26a , N.M. Bolnet 136 , M. Bomben 78 , M. Bona 75 , M. Boonekamp 136 , S. Bordoni 78 , C. Borer 17 , A. Borisov 128 , G. Borissov 71 , I. Borjanovic 13a , M. Borri 82 , S. Borroni 87 , J. Bortfeldt 98 , V. Bortolotto 134a,134b , K. Bos 105 , D. Boscherini 20a , M. Bosman 12 , H. Boterenbrood 105 , J. Bouchami 93 , J. Boudreau 123 , E.V. Bouhova-Thacker 71 , D. Boumediene 34 , C. Bourdarios 115 , N. Bousson 83 , A. Boveia 31 , J. Boyd 30 , I.R. Boyko 64 , I. Bozovic-Jelisavcic 13b , J. Bracinik 18 , P. Branchini 134a , A. Brandt 8 , G. Brandt 118 , O. Brandt 54 , U. Bratzler 156 , B. Brau 84 , J.E. Brau 114 , H.M. Braun 175,∗ , S.F. Brazzale 164a,164c , B. Brelier 158 , J. Bremer 30 , K. Brendlinger 120 , R. Brenner 166 , S. Bressler 172 , D. Britton 53 , F.M. Brochu 28 , I. Brock 21 , R. Brock 88 , F. Broggi 89a , C. Bromberg 88 , J. Bronner 99 , G. Brooijmans 35 , T. Brooks 76 , W.K. Brooks 32b , G. Brown 82 , H. Brown 8 , P.A. Bruckman de Renstrom 39 , D. Bruncko 144b , R. Bruneliere 48 , S. Brunet 60 , A. Bruni 20a , G. Bruni 20a , M. Bruschi 20a , T. Buanes 14 , Q. Buat 55 , F. Bucci 49 , J. Buchanan 118 , P. Buchholz 141 , R.M. Buckingham 118 , A.G. Buckley 46 , S.I. Buda 26a , I.A. Budagov 64 , B. Budick 108 , V. Büscher 81 , L. Bugge 117 , O. Bulekov 96 , A.C. Bundock 73 , M. Bunse 43 , T. Buran 117 , H. Burckhart 30 , S. Burdin 73 , T. Burgess 14 , S. Burke 129 , E. Busato 34 , P. Bussey 53 , C.P. Buszello 166 , B. Butler 143 , J.M. Butler 22 , C.M. Buttar 53 , J.M. Butterworth 77 , W. Buttinger 28 , M. Byszewski 30 , S. Cabrera Urbán 167 , D. Caforio 20a,20b , O. Cakir 4a , P. Calafiura 15 , G. Calderini 78 , P. Calfayan 98 , R. Calkins 106 , L.P. Caloba 24a , R. Caloi 132a,132b , D. Calvet 34 , S. Calvet 34 , R. Camacho Toro 34 , P. Camarri 133a,133b , D. Cameron 117 , L.M. Caminada 15 , R. Caminal Armadans 12 , S. Campana 30 , M. Campanelli 77 , V. Canale 102a,102b , F. Canelli 31 , A. Canepa 159a , J. Cantero 80 , R. Cantrill 76 , L. Capasso 102a,102b , M.D.M. Capeans Garrido 30 , I. Caprini 26a , M. Caprini 26a , D. Capriotti 99 , M. Capua 37a,37b , R. Caputo 81 , R. Cardarelli 133a , T. Carli 30 , G. Carlino 102a , L. Carminati 89a,89b , B. Caron 85 , S. Caron 104 , E. Carquin 32b , G.D. Carrillo-Montoya 145b , A.A. Carter 75 , J.R. Carter 28 , J. Carvalho 124a,h , D. Casadei 108 , M.P. Casado 12 , M. Cascella 122a,122b , C. Caso 50a,50b,∗ , A.M. Castaneda Hernandez 173,i , E. Castaneda-Miranda 173 , V. Castillo Gimenez 167 , N.F. Castro 124a , G. Cataldi 72a , P. Catastini 57 , A. Catinaccio 30 , J.R. Catmore 30 , A. Cattai 30 , G. Cattani 133a,133b , S. Caughron 88 , V. Cavaliere 165 , P. Cavalleri 78 , D. Cavalli 89a , M. Cavalli-Sforza 12 , V. Cavasinni 122a,122b , F. Ceradini 134a,134b , A.S. Cerqueira 24b , A. Cerri 30 , L. Cerrito 75 , F. Cerutti 47 , S.A. Cetin 19b , A. Chafaq 135a , D. Chakraborty 106 , I. Chalupkova 126 , K. Chan 3 , P. Chang 165 , B. Chapleau 85 , J.D. Chapman 28 , J.W. Chapman 87 , E. Chareyre 78 , D.G. Charlton 18 , V. Chavda 82 , C.A. Chavez Barajas 30 , S. Cheatham 85 , S. Chekanov 6 , S.V. Chekulaev 159a , G.A. Chelkov 64 , M.A. Chelstowska 104 , C. Chen 63 , H. Chen 25 , S. Chen 33c , X. Chen 173 , Y. Chen 35 , Y. Cheng 31 , A. Cheplakov 64 , R. Cherkaoui El Moursli 135e , V. Chernyatin 25 , E. Cheu 7 , S.L. Cheung 158 , L. Chevalier 136 , G. Chiefari 102a,102b , L. Chikovani 51a,∗ , J.T. Childers 30 , A. Chilingarov 71 , G. Chiodini 72a , A.S. Chisholm 18 , R.T. Chislett 77 , A. Chitan 26a , M.V. Chizhov 64 , G. Choudalakis 31 , S. Chouridou 137 , I.A. Christidi 77 , A. Christov 48 , D. Chromek-Burckhart 30 , M.L. Chu 151 , J. Chudoba 125 , G. Ciapetti 132a,132b , A.K. Ciftci 4a , R. Ciftci 4a , D. Cinca 34 , V. Cindro 74 , C. Ciocca 20a,20b , A. Ciocio 15 , M. Cirilli 87 , P. Cirkovic 13b , Z.H. Citron 172 , M. Citterio 89a , M. Ciubancan 26a , A. Clark 49 , P.J. Clark 46 , R.N. Clarke 15 , W. Cleland 123 , J.C. Clemens 83 , B. Clement 55 , C. Clement 146a,146b , Y. Coadou 83 , M. Cobal 164a,164c , A. Coccaro 138 , J. Cochran 63 , L. Coffey 23 , J.G. Cogan 143 , J. Coggeshall 165 , E. Cogneras 178 , J. Colas 5 , S. Cole 106 , A.P. Colijn 105 , N.J. Collins 18 , C. Collins-Tooth 53 , J. Collot 55 , T. Colombo 119a,119b , G. Colon 84 , G. Compostella 99 , P. Conde Muiño 124a , E. Coniavitis 166 , M.C. Conidi 12 , S.M. Consonni 89a,89b , V. Consorti 48 , S. Constantinescu 26a , C. Conta 119a,119b , G. Conti 57 , F. Conventi 102a,j , M. Cooke 15 , B.D. Cooper 77 , A.M. Cooper-Sarkar 118 , K. Copic 15 , T. Cornelissen 175 , M. Corradi 20a , F. Corriveau 85,k , A. Cortes-Gonzalez 165 , G. Cortiana 99 , G. Costa 89a , M.J. Costa 167 , D. Costanzo 139 , D. Côté 30 , L. Courneyea 169 , G. Cowan 76 , C. Cowden 28 , B.E. Cox 82 , K. Cranmer 108 , F. Crescioli 122a,122b , M. Cristinziani 21 , G. Crosetti 37a,37b , S. Crépé-Renaudin 55 , C.-M. Cuciuc 26a , C. Cuenca Almenar 176 ,.

(10) ATLAS Collaboration / Physics Letters B 719 (2013) 242–260. 251. T. Cuhadar Donszelmann 139 , J. Cummings 176 , M. Curatolo 47 , C.J. Curtis 18 , C. Cuthbert 150 , P. Cwetanski 60 , H. Czirr 141 , P. Czodrowski 44 , Z. Czyczula 176 , S. D’Auria 53 , M. D’Onofrio 73 , A. D’Orazio 132a,132b , M.J. Da Cunha Sargedas De Sousa 124a , C. Da Via 82 , W. Dabrowski 38 , A. Dafinca 118 , T. Dai 87 , C. Dallapiccola 84 , M. Dam 36 , M. Dameri 50a,50b , D.S. Damiani 137 , H.O. Danielsson 30 , V. Dao 49 , G. Darbo 50a , G.L. Darlea 26b , J.A. Dassoulas 42 , W. Davey 21 , T. Davidek 126 , N. Davidson 86 , R. Davidson 71 , E. Davies 118,c , M. Davies 93 , O. Davignon 78 , A.R. Davison 77 , Y. Davygora 58a , E. Dawe 142 , I. Dawson 139 , R.K. Daya-Ishmukhametova 23 , K. De 8 , R. de Asmundis 102a , S. De Castro 20a,20b , S. De Cecco 78 , J. de Graat 98 , N. De Groot 104 , P. de Jong 105 , C. De La Taille 115 , H. De la Torre 80 , F. De Lorenzi 63 , L. de Mora 71 , L. De Nooij 105 , D. De Pedis 132a , A. De Salvo 132a , U. De Sanctis 164a,164c , A. De Santo 149 , J.B. De Vivie De Regie 115 , G. De Zorzi 132a,132b , W.J. Dearnaley 71 , R. Debbe 25 , C. Debenedetti 46 , B. Dechenaux 55 , D.V. Dedovich 64 , J. Degenhardt 120 , J. Del Peso 80 , T. Del Prete 122a,122b , T. Delemontex 55 , M. Deliyergiyev 74 , A. Dell’Acqua 30 , L. Dell’Asta 22 , M. Della Pietra 102a,j , D. della Volpe 102a,102b , M. Delmastro 5 , P.A. Delsart 55 , C. Deluca 105 , S. Demers 176 , M. Demichev 64 , B. Demirkoz 12,l , S.P. Denisov 128 , D. Derendarz 39 , J.E. Derkaoui 135d , F. Derue 78 , P. Dervan 73 , K. Desch 21 , E. Devetak 148 , P.O. Deviveiros 105 , A. Dewhurst 129 , B. DeWilde 148 , S. Dhaliwal 158 , R. Dhullipudi 25,m , A. Di Ciaccio 133a,133b , L. Di Ciaccio 5 , C. Di Donato 102a,102b , A. Di Girolamo 30 , B. Di Girolamo 30 , S. Di Luise 134a,134b , A. Di Mattia 173 , B. Di Micco 30 , R. Di Nardo 47 , A. Di Simone 133a,133b , R. Di Sipio 20a,20b , M.A. Diaz 32a , E.B. Diehl 87 , J. Dietrich 42 , T.A. Dietzsch 58a , S. Diglio 86 , K. Dindar Yagci 40 , J. Dingfelder 21 , F. Dinut 26a , C. Dionisi 132a,132b , P. Dita 26a , S. Dita 26a , F. Dittus 30 , F. Djama 83 , T. Djobava 51b , M.A.B. do Vale 24c , A. Do Valle Wemans 124a,n , T.K.O. Doan 5 , M. Dobbs 85 , D. Dobos 30 , E. Dobson 30,o , J. Dodd 35 , C. Doglioni 49 , T. Doherty 53 , Y. Doi 65,∗ , J. Dolejsi 126 , I. Dolenc 74 , Z. Dolezal 126 , B.A. Dolgoshein 96,∗ , T. Dohmae 155 , M. Donadelli 24d , J. Donini 34 , J. Dopke 30 , A. Doria 102a , A. Dos Anjos 173 , A. Dotti 122a,122b , M.T. Dova 70 , A.D. Doxiadis 105 , A.T. Doyle 53 , N. Dressnandt 120 , M. Dris 10 , J. Dubbert 99 , S. Dube 15 , E. Duchovni 172 , G. Duckeck 98 , D. Duda 175 , A. Dudarev 30 , F. Dudziak 63 , M. Dührssen 30 , I.P. Duerdoth 82 , L. Duflot 115 , M.-A. Dufour 85 , L. Duguid 76 , M. Dunford 58a , H. Duran Yildiz 4a , R. Duxfield 139 , M. Dwuznik 38 , M. Düren 52 , W.L. Ebenstein 45 , J. Ebke 98 , S. Eckweiler 81 , K. Edmonds 81 , W. Edson 2 , C.A. Edwards 76 , N.C. Edwards 53 , W. Ehrenfeld 42 , T. Eifert 143 , G. Eigen 14 , K. Einsweiler 15 , E. Eisenhandler 75 , T. Ekelof 166 , M. El Kacimi 135c , M. Ellert 166 , S. Elles 5 , F. Ellinghaus 81 , K. Ellis 75 , N. Ellis 30 , J. Elmsheuser 98 , M. Elsing 30 , D. Emeliyanov 129 , R. Engelmann 148 , A. Engl 98 , B. Epp 61 , J. Erdmann 54 , A. Ereditato 17 , D. Eriksson 146a , J. Ernst 2 , M. Ernst 25 , J. Ernwein 136 , D. Errede 165 , S. Errede 165 , E. Ertel 81 , M. Escalier 115 , H. Esch 43 , C. Escobar 123 , X. Espinal Curull 12 , B. Esposito 47 , F. Etienne 83 , A.I. Etienvre 136 , E. Etzion 153 , D. Evangelakou 54 , H. Evans 60 , L. Fabbri 20a,20b , C. Fabre 30 , R.M. Fakhrutdinov 128 , S. Falciano 132a , Y. Fang 33a , M. Fanti 89a,89b , A. Farbin 8 , A. Farilla 134a , J. Farley 148 , T. Farooque 158 , S. Farrell 163 , S.M. Farrington 170 , P. Farthouat 30 , F. Fassi 167 , P. Fassnacht 30 , D. Fassouliotis 9 , B. Fatholahzadeh 158 , A. Favareto 89a,89b , L. Fayard 115 , S. Fazio 37a,37b , R. Febbraro 34 , P. Federic 144a , O.L. Fedin 121 , W. Fedorko 88 , M. Fehling-Kaschek 48 , L. Feligioni 83 , C. Feng 33d , E.J. Feng 6 , A.B. Fenyuk 128 , J. Ferencei 144b , W. Fernando 6 , S. Ferrag 53 , J. Ferrando 53 , V. Ferrara 42 , A. Ferrari 166 , P. Ferrari 105 , R. Ferrari 119a , D.E. Ferreira de Lima 53 , A. Ferrer 167 , D. Ferrere 49 , C. Ferretti 87 , A. Ferretto Parodi 50a,50b , M. Fiascaris 31 , F. Fiedler 81 , A. Filipčič 74 , F. Filthaut 104 , M. Fincke-Keeler 169 , M.C.N. Fiolhais 124a,h , L. Fiorini 167 , A. Firan 40 , G. Fischer 42 , M.J. Fisher 109 , M. Flechl 48 , I. Fleck 141 , J. Fleckner 81 , P. Fleischmann 174 , S. Fleischmann 175 , T. Flick 175 , A. Floderus 79 , L.R. Flores Castillo 173 , A.C. Florez Bustos 159b , M.J. Flowerdew 99 , T. Fonseca Martin 17 , A. Formica 136 , A. Forti 82 , D. Fortin 159a , D. Fournier 115 , A.J. Fowler 45 , H. Fox 71 , P. Francavilla 12 , M. Franchini 20a,20b , S. Franchino 119a,119b , D. Francis 30 , T. Frank 172 , M. Franklin 57 , S. Franz 30 , M. Fraternali 119a,119b , S. Fratina 120 , S.T. French 28 , C. Friedrich 42 , F. Friedrich 44 , R. Froeschl 30 , D. Froidevaux 30 , J.A. Frost 28 , C. Fukunaga 156 , E. Fullana Torregrosa 30 , B.G. Fulsom 143 , J. Fuster 167 , C. Gabaldon 30 , O. Gabizon 172 , T. Gadfort 25 , S. Gadomski 49 , G. Gagliardi 50a,50b , P. Gagnon 60 , C. Galea 98 , B. Galhardo 124a , E.J. Gallas 118 , V. Gallo 17 , B.J. Gallop 129 , P. Gallus 125 , K.K. Gan 109 , Y.S. Gao 143,f , A. Gaponenko 15 , F. Garberson 176 , M. Garcia-Sciveres 15 , C. García 167 , J.E. García Navarro 167 , R.W. Gardner 31 , N. Garelli 30 , H. Garitaonandia 105 , V. Garonne 30 , C. Gatti 47 , G. Gaudio 119a , B. Gaur 141 , L. Gauthier 136 , P. Gauzzi 132a,132b , I.L. Gavrilenko 94 , C. Gay 168 , G. Gaycken 21 , E.N. Gazis 10 , P. Ge 33d , Z. Gecse 168 , C.N.P. Gee 129 , D.A.A. Geerts 105 , Ch. Geich-Gimbel 21 , K. Gellerstedt 146a,146b , C. Gemme 50a ,.

(11) 252. ATLAS Collaboration / Physics Letters B 719 (2013) 242–260. A. Gemmell 53 , M.H. Genest 55 , S. Gentile 132a,132b , M. George 54 , S. George 76 , P. Gerlach 175 , A. Gershon 153 , C. Geweniger 58a , H. Ghazlane 135b , N. Ghodbane 34 , B. Giacobbe 20a , S. Giagu 132a,132b , V. Giakoumopoulou 9 , V. Giangiobbe 12 , F. Gianotti 30 , B. Gibbard 25 , A. Gibson 158 , S.M. Gibson 30 , M. Gilchriese 15 , D. Gillberg 29 , A.R. Gillman 129 , D.M. Gingrich 3,e , J. Ginzburg 153 , N. Giokaris 9 , M.P. Giordani 164c , R. Giordano 102a,102b , F.M. Giorgi 16 , P. Giovannini 99 , P.F. Giraud 136 , D. Giugni 89a , M. Giunta 93 , B.K. Gjelsten 117 , L.K. Gladilin 97 , C. Glasman 80 , J. Glatzer 21 , A. Glazov 42 , K.W. Glitza 175 , G.L. Glonti 64 , J.R. Goddard 75 , J. Godfrey 142 , J. Godlewski 30 , M. Goebel 42 , T. Göpfert 44 , C. Goeringer 81 , C. Gössling 43 , S. Goldfarb 87 , T. Golling 176 , A. Gomes 124a,b , L.S. Gomez Fajardo 42 , R. Gonçalo 76 , J. Goncalves Pinto Firmino Da Costa 42 , L. Gonella 21 , S. González de la Hoz 167 , G. Gonzalez Parra 12 , M.L. Gonzalez Silva 27 , S. Gonzalez-Sevilla 49 , J.J. Goodson 148 , L. Goossens 30 , P.A. Gorbounov 95 , H.A. Gordon 25 , I. Gorelov 103 , G. Gorfine 175 , B. Gorini 30 , E. Gorini 72a,72b , A. Gorišek 74 , E. Gornicki 39 , A.T. Goshaw 6 , M. Gosselink 105 , M.I. Gostkin 64 , I. Gough Eschrich 163 , M. Gouighri 135a , D. Goujdami 135c , M.P. Goulette 49 , A.G. Goussiou 138 , C. Goy 5 , S. Gozpinar 23 , I. Grabowska-Bold 38 , P. Grafström 20a,20b , K.-J. Grahn 42 , E. Gramstad 117 , F. Grancagnolo 72a , S. Grancagnolo 16 , V. Grassi 148 , V. Gratchev 121 , N. Grau 35 , H.M. Gray 30 , J.A. Gray 148 , E. Graziani 134a , O.G. Grebenyuk 121 , T. Greenshaw 73 , Z.D. Greenwood 25,m , K. Gregersen 36 , I.M. Gregor 42 , P. Grenier 143 , J. Griffiths 8 , N. Grigalashvili 64 , A.A. Grillo 137 , S. Grinstein 12 , Ph. Gris 34 , Y.V. Grishkevich 97 , J.-F. Grivaz 115 , E. Gross 172 , J. Grosse-Knetter 54 , J. Groth-Jensen 172 , K. Grybel 141 , D. Guest 176 , C. Guicheney 34 , E. Guido 50a,50b , S. Guindon 54 , U. Gul 53 , J. Gunther 125 , B. Guo 158 , J. Guo 35 , P. Gutierrez 111 , N. Guttman 153 , O. Gutzwiller 173 , C. Guyot 136 , C. Gwenlan 118 , C.B. Gwilliam 73 , A. Haas 108 , S. Haas 30 , C. Haber 15 , H.K. Hadavand 8 , D.R. Hadley 18 , P. Haefner 21 , F. Hahn 30 , Z. Hajduk 39 , H. Hakobyan 177 , D. Hall 118 , K. Hamacher 175 , P. Hamal 113 , K. Hamano 86 , M. Hamer 54 , A. Hamilton 145b,p , S. Hamilton 161 , L. Han 33b , K. Hanagaki 116 , K. Hanawa 160 , M. Hance 15 , C. Handel 81 , P. Hanke 58a , J.R. Hansen 36 , J.B. Hansen 36 , J.D. Hansen 36 , P.H. Hansen 36 , P. Hansson 143 , K. Hara 160 , T. Harenberg 175 , S. Harkusha 90 , D. Harper 87 , R.D. Harrington 46 , O.M. Harris 138 , J. Hartert 48 , F. Hartjes 105 , T. Haruyama 65 , A. Harvey 56 , S. Hasegawa 101 , Y. Hasegawa 140 , S. Hassani 136 , S. Haug 17 , M. Hauschild 30 , R. Hauser 88 , M. Havranek 21 , C.M. Hawkes 18 , R.J. Hawkings 30 , A.D. Hawkins 79 , T. Hayakawa 66 , T. Hayashi 160 , D. Hayden 76 , C.P. Hays 118 , H.S. Hayward 73 , S.J. Haywood 129 , S.J. Head 18 , V. Hedberg 79 , L. Heelan 8 , S. Heim 120 , B. Heinemann 15 , S. Heisterkamp 36 , L. Helary 22 , C. Heller 98 , M. Heller 30 , S. Hellman 146a,146b , D. Hellmich 21 , C. Helsens 12 , R.C.W. Henderson 71 , M. Henke 58a , A. Henrichs 176 , A.M. Henriques Correia 30 , S. Henrot-Versille 115 , C. Hensel 54 , C.M. Hernandez 8 , Y. Hernández Jiménez 167 , R. Herrberg 16 , G. Herten 48 , R. Hertenberger 98 , L. Hervas 30 , G.G. Hesketh 77 , N.P. Hessey 105 , E. Higón-Rodriguez 167 , J.C. Hill 28 , K.H. Hiller 42 , S. Hillert 21 , S.J. Hillier 18 , I. Hinchliffe 15 , E. Hines 120 , M. Hirose 116 , F. Hirsch 43 , D. Hirschbuehl 175 , J. Hobbs 148 , N. Hod 153 , M.C. Hodgkinson 139 , P. Hodgson 139 , A. Hoecker 30 , M.R. Hoeferkamp 103 , J. Hoffman 40 , D. Hoffmann 83 , M. Hohlfeld 81 , M. Holder 141 , S.O. Holmgren 146a , T. Holy 127 , J.L. Holzbauer 88 , T.M. Hong 120 , L. Hooft van Huysduynen 108 , S. Horner 48 , J.-Y. Hostachy 55 , S. Hou 151 , A. Hoummada 135a , J. Howard 118 , J. Howarth 82 , I. Hristova 16 , J. Hrivnac 115 , T. Hryn’ova 5 , P.J. Hsu 81 , S.-C. Hsu 15 , D. Hu 35 , Z. Hubacek 127 , F. Hubaut 83 , F. Huegging 21 , A. Huettmann 42 , T.B. Huffman 118 , E.W. Hughes 35 , G. Hughes 71 , M. Huhtinen 30 , M. Hurwitz 15 , N. Huseynov 64,q , J. Huston 88 , J. Huth 57 , G. Iacobucci 49 , G. Iakovidis 10 , M. Ibbotson 82 , I. Ibragimov 141 , L. Iconomidou-Fayard 115 , J. Idarraga 115 , P. Iengo 102a , O. Igonkina 105 , Y. Ikegami 65 , M. Ikeno 65 , D. Iliadis 154 , N. Ilic 158 , T. Ince 99 , P. Ioannou 9 , M. Iodice 134a , K. Iordanidou 9 , V. Ippolito 132a,132b , A. Irles Quiles 167 , C. Isaksson 166 , M. Ishino 67 , M. Ishitsuka 157 , R. Ishmukhametov 109 , C. Issever 118 , S. Istin 19a , A.V. Ivashin 128 , W. Iwanski 39 , H. Iwasaki 65 , J.M. Izen 41 , V. Izzo 102a , B. Jackson 120 , J.N. Jackson 73 , P. Jackson 1 , M.R. Jaekel 30 , V. Jain 60 , K. Jakobs 48 , S. Jakobsen 36 , T. Jakoubek 125 , J. Jakubek 127 , D.O. Jamin 151 , D.K. Jana 111 , E. Jansen 77 , H. Jansen 30 , J. Janssen 21 , A. Jantsch 99 , M. Janus 48 , R.C. Jared 173 , G. Jarlskog 79 , L. Jeanty 57 , I. Jen-La Plante 31 , D. Jennens 86 , P. Jenni 30 , A.E. Loevschall-Jensen 36 , P. Jež 36 , S. Jézéquel 5 , M.K. Jha 20a , H. Ji 173 , W. Ji 81 , J. Jia 148 , Y. Jiang 33b , M. Jimenez Belenguer 42 , S. Jin 33a , O. Jinnouchi 157 , M.D. Joergensen 36 , D. Joffe 40 , M. Johansen 146a,146b , K.E. Johansson 146a , P. Johansson 139 , S. Johnert 42 , K.A. Johns 7 , K. Jon-And 146a,146b , G. Jones 170 , R.W.L. Jones 71 , T.J. Jones 73 , C. Joram 30 , P.M. Jorge 124a , K.D. Joshi 82 , J. Jovicevic 147 , T. Jovin 13b , X. Ju 173 , C.A. Jung 43 , R.M. Jungst 30 , V. Juranek 125 , P. Jussel 61 , A. Juste Rozas 12 , S. Kabana 17 ,.

(12) ATLAS Collaboration / Physics Letters B 719 (2013) 242–260. 253. M. Kaci 167 , A. Kaczmarska 39 , P. Kadlecik 36 , M. Kado 115 , H. Kagan 109 , M. Kagan 57 , E. Kajomovitz 152 , S. Kalinin 175 , L.V. Kalinovskaya 64 , S. Kama 40 , N. Kanaya 155 , M. Kaneda 30 , S. Kaneti 28 , T. Kanno 157 , V.A. Kantserov 96 , J. Kanzaki 65 , B. Kaplan 108 , A. Kapliy 31 , J. Kaplon 30 , D. Kar 53 , M. Karagounis 21 , K. Karakostas 10 , M. Karnevskiy 42 , V. Kartvelishvili 71 , A.N. Karyukhin 128 , L. Kashif 173 , G. Kasieczka 58b , R.D. Kass 109 , A. Kastanas 14 , M. Kataoka 5 , Y. Kataoka 155 , E. Katsoufis 10 , J. Katzy 42 , V. Kaushik 7 , K. Kawagoe 69 , T. Kawamoto 155 , G. Kawamura 81 , M.S. Kayl 105 , S. Kazama 155 , V.A. Kazanin 107 , M.Y. Kazarinov 64 , R. Keeler 169 , P.T. Keener 120 , R. Kehoe 40 , M. Keil 54 , G.D. Kekelidze 64 , J.S. Keller 138 , M. Kenyon 53 , O. Kepka 125 , N. Kerschen 30 , B.P. Kerševan 74 , S. Kersten 175 , K. Kessoku 155 , J. Keung 158 , F. Khalil-zada 11 , H. Khandanyan 146a,146b , A. Khanov 112 , D. Kharchenko 64 , A. Khodinov 96 , A. Khomich 58a , T.J. Khoo 28 , G. Khoriauli 21 , A. Khoroshilov 175 , V. Khovanskiy 95 , E. Khramov 64 , J. Khubua 51b , H. Kim 146a,146b , S.H. Kim 160 , N. Kimura 171 , O. Kind 16 , B.T. King 73 , M. King 66 , R.S.B. King 118 , J. Kirk 129 , A.E. Kiryunin 99 , T. Kishimoto 66 , D. Kisielewska 38 , T. Kitamura 66 , T. Kittelmann 123 , K. Kiuchi 160 , E. Kladiva 144b , M. Klein 73 , U. Klein 73 , K. Kleinknecht 81 , M. Klemetti 85 , A. Klier 172 , P. Klimek 146a,146b , A. Klimentov 25 , R. Klingenberg 43 , J.A. Klinger 82 , E.B. Klinkby 36 , T. Klioutchnikova 30 , P.F. Klok 104 , S. Klous 105 , E.-E. Kluge 58a , T. Kluge 73 , P. Kluit 105 , S. Kluth 99 , E. Kneringer 61 , E.B.F.G. Knoops 83 , A. Knue 54 , B.R. Ko 45 , T. Kobayashi 155 , M. Kobel 44 , M. Kocian 143 , P. Kodys 126 , K. Köneke 30 , A.C. König 104 , S. Koenig 81 , L. Köpke 81 , F. Koetsveld 104 , P. Koevesarki 21 , T. Koffas 29 , E. Koffeman 105 , L.A. Kogan 118 , S. Kohlmann 175 , F. Kohn 54 , Z. Kohout 127 , T. Kohriki 65 , T. Koi 143 , G.M. Kolachev 107,∗ , H. Kolanoski 16 , V. Kolesnikov 64 , I. Koletsou 89a , J. Koll 88 , A.A. Komar 94 , Y. Komori 155 , T. Kondo 65 , T. Kono 42,r , A.I. Kononov 48 , R. Konoplich 108,s , N. Konstantinidis 77 , R. Kopeliansky 152 , S. Koperny 38 , K. Korcyl 39 , K. Kordas 154 , A. Korn 118 , A. Korol 107 , I. Korolkov 12 , E.V. Korolkova 139 , V.A. Korotkov 128 , O. Kortner 99 , S. Kortner 99 , V.V. Kostyukhin 21 , S. Kotov 99 , V.M. Kotov 64 , A. Kotwal 45 , C. Kourkoumelis 9 , V. Kouskoura 154 , A. Koutsman 159a , R. Kowalewski 169 , T.Z. Kowalski 38 , W. Kozanecki 136 , A.S. Kozhin 128 , V. Kral 127 , V.A. Kramarenko 97 , G. Kramberger 74 , M.W. Krasny 78 , A. Krasznahorkay 108 , J.K. Kraus 21 , S. Kreiss 108 , F. Krejci 127 , J. Kretzschmar 73 , N. Krieger 54 , P. Krieger 158 , K. Kroeninger 54 , H. Kroha 99 , J. Kroll 120 , J. Kroseberg 21 , J. Krstic 13a , U. Kruchonak 64 , H. Krüger 21 , T. Kruker 17 , N. Krumnack 63 , Z.V. Krumshteyn 64 , M.K. Kruse 45 , T. Kubota 86 , S. Kuday 4a , S. Kuehn 48 , A. Kugel 58c , T. Kuhl 42 , D. Kuhn 61 , V. Kukhtin 64 , Y. Kulchitsky 90 , S. Kuleshov 32b , C. Kummer 98 , M. Kuna 78 , J. Kunkle 120 , A. Kupco 125 , H. Kurashige 66 , M. Kurata 160 , Y.A. Kurochkin 90 , V. Kus 125 , E.S. Kuwertz 147 , M. Kuze 157 , J. Kvita 142 , R. Kwee 16 , A. La Rosa 49 , L. La Rotonda 37a,37b , L. Labarga 80 , J. Labbe 5 , S. Lablak 135a , C. Lacasta 167 , F. Lacava 132a,132b , J. Lacey 29 , H. Lacker 16 , D. Lacour 78 , V.R. Lacuesta 167 , E. Ladygin 64 , R. Lafaye 5 , B. Laforge 78 , T. Lagouri 176 , S. Lai 48 , E. Laisne 55 , L. Lambourne 77 , C.L. Lampen 7 , W. Lampl 7 , E. Lancon 136 , U. Landgraf 48 , M.P.J. Landon 75 , V.S. Lang 58a , C. Lange 42 , A.J. Lankford 163 , F. Lanni 25 , K. Lantzsch 175 , A. Lanza 119a , S. Laplace 78 , C. Lapoire 21 , J.F. Laporte 136 , T. Lari 89a , A. Larner 118 , M. Lassnig 30 , P. Laurelli 47 , V. Lavorini 37a,37b , W. Lavrijsen 15 , P. Laycock 73 , O. Le Dortz 78 , E. Le Guirriec 83 , E. Le Menedeu 12 , T. LeCompte 6 , F. Ledroit-Guillon 55 , H. Lee 105 , J.S.H. Lee 116 , S.C. Lee 151 , L. Lee 176 , M. Lefebvre 169 , M. Legendre 136 , F. Legger 98 , C. Leggett 15 , M. Lehmacher 21 , G. Lehmann Miotto 30 , A.G. Leister 176 , M.A.L. Leite 24d , R. Leitner 126 , D. Lellouch 172 , B. Lemmer 54 , V. Lendermann 58a , K.J.C. Leney 145b , T. Lenz 105 , G. Lenzen 175 , B. Lenzi 30 , K. Leonhardt 44 , S. Leontsinis 10 , F. Lepold 58a , C. Leroy 93 , J.-R. Lessard 169 , C.G. Lester 28 , C.M. Lester 120 , J. Levêque 5 , D. Levin 87 , L.J. Levinson 172 , A. Lewis 118 , G.H. Lewis 108 , A.M. Leyko 21 , M. Leyton 16 , B. Li 33b , B. Li 83 , H. Li 148 , H.L. Li 31 , S. Li 33b,t , X. Li 87 , Z. Liang 118,u , H. Liao 34 , B. Liberti 133a , P. Lichard 30 , M. Lichtnecker 98 , K. Lie 165 , W. Liebig 14 , C. Limbach 21 , A. Limosani 86 , M. Limper 62 , S.C. Lin 151,v , F. Linde 105 , J.T. Linnemann 88 , E. Lipeles 120 , A. Lipniacka 14 , T.M. Liss 165 , D. Lissauer 25 , A. Lister 49 , A.M. Litke 137 , C. Liu 29 , D. Liu 151 , H. Liu 87 , J.B. Liu 87 , L. Liu 87 , M. Liu 33b , Y. Liu 33b , M. Livan 119a,119b , S.S.A. Livermore 118 , A. Lleres 55 , J. Llorente Merino 80 , S.L. Lloyd 75 , E. Lobodzinska 42 , P. Loch 7 , W.S. Lockman 137 , T. Loddenkoetter 21 , F.K. Loebinger 82 , A. Loginov 176 , C.W. Loh 168 , T. Lohse 16 , K. Lohwasser 48 , M. Lokajicek 125 , V.P. Lombardo 5 , R.E. Long 71 , L. Lopes 124a , D. Lopez Mateos 57 , J. Lorenz 98 , N. Lorenzo Martinez 115 , M. Losada 162 , P. Loscutoff 15 , F. Lo Sterzo 132a,132b , M.J. Losty 159a,∗ , X. Lou 41 , A. Lounis 115 , K.F. Loureiro 162 , J. Love 6 , P.A. Love 71 , A.J. Lowe 143,f , F. Lu 33a , H.J. Lubatti 138 , C. Luci 132a,132b , A. Lucotte 55 , A. Ludwig 44 , D. Ludwig 42 , I. Ludwig 48 , J. Ludwig 48 , F. Luehring 60 , G. Luijckx 105 , W. Lukas 61 , L. Luminari 132a , E. Lund 117 , B. Lund-Jensen 147 , B. Lundberg 79 ,.